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Theoretical explorations of the evolution of long-distance dispersal.
Muller-Landau, Helene1, Keymer, Juan1, Levin, Simon1, Pacala, Stephen 1, 1
ABSTRACT- The same characteristics that make it difficult to assess the magnitude and consequences of long-distance dispersal also complicate theoretical treatment of its evolution. In order to investigate the evolution of a trait, we need to know the fitness consequences (both payoffs and costs) of different trait values in competition with other types. However, little is known about the costs of long-distance dispersal – about whether or how long-distance dispersal trades off with shorter-distance dispersal, fecundity and/or establishment ability. Furthermore, the payoffs of long-distance dispersal are very difficult to quantify because they emerge from rare events over large spatial scales and multiple generations. The main benefits derive from the ability of distantly dispersed offspring to escape the local correlation length of the population, colonizing patches in which rapid local population expansion can subsequently occur. We use spatially explicit models to explore these advantages of long-distance dispersal. We employ moment methods to analytically represent the correlation structure that emerges and its effects on the fitness of different dispersal types. We combine these approximations with techniques of adaptive dynamics to explore the evolution of dispersal under different assumptions about its costs. Finally, we show how these methods can be applied to the evolution of long-distance dispersal in a variety of scenarios, including large-scale disturbances, range expansions, and metapopulation extinctions driven by specialized pests.
KEY WORDS: dispersal, moment methods, adaptive dynamics, spatial ecology